Method for determining the total pressure of a high-speed free jet wind tunnel

Abstract

The present application belongs to the field of experimental aerodynamics, and particularly relates to a method for determining the total pressure of a high-speed free jet wind tunnel. The method for determining the total pressure of the high-speed free jet wind tunnel comprises selecting basic test data, fitting a curve, calculating the wind tunnel static pressure to be simulated according to the simulated height, calculating the plenum total pressure, and calculating the total pressure of the ejector. The method for determining the total pressure of the high-speed free jet wind tunnel finds and fits a quadratic curve of the plenum total pressure and the total pressure of the ejector under the condition of the same test Mach number and similar model blockage by analyzing the data of previous tests, establishes the quadratic function relationship between the plenum total pressure and the total pressure of the ejector, and obtains the total pressure of the ejector corresponding to any test cabin static pressure under the condition of the same test Mach number and similar model blockage, thereby saving a large number of test runs and energy consumption, improving the experimental efficiency of the high-speed free jet wind tunnel, and having engineering practical value.

Description

Technical Field

[0001] This invention belongs to the field of experimental aerodynamics, specifically relating to a method for determining the total ejection pressure of a high-speed free jet wind tunnel. Background Technology

[0002] Wind tunnels artificially generate and control airflow, simulating the airflow around an object to conduct aerodynamic research and aircraft development based on the principles of relativity and similarity of motion. Wind tunnel tests often require different wind tunnel static pressures to simulate different altitudes. This is typically achieved by using an ejector installed downstream of the diffuser to expel air downstream, reducing the back pressure and thus altering the wind tunnel static pressure to simulate different test altitudes.

[0003] However, in high-speed free-jet wind tunnel tests, due to the total pressure in the anterior chamber... P 0 and total ejection pressure P 0p The coupling effect of wind tunnel static pressure makes it difficult to directly determine the ejector total pressure through calculation. Currently, the ejector total pressure is basically determined through experiments. Therefore, if parameters such as the experimental static pressure are changed, a large number of commissioning runs are required to redetermine the ejector total pressure.

[0004] Currently, there is an urgent need to develop a method for determining the total ejection pressure of a high-speed free-jet wind tunnel. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for determining the total ejection pressure of a high-speed free jet wind tunnel, so as to overcome the defects of the prior art.

[0006] The method for determining the total ejector pressure of a high-speed free-jet wind tunnel according to the present invention includes the following steps: S01. Select experimental data; By selecting three or more existing test data with the same experimental Mach number M, similar model blockage degree, and different ejector total pressure, the corresponding anterior chamber total pressure and ejector total pressure sequences were obtained: P 01 、P 0p1 ，P 02 、P 0p2 ，P 03 、P 0p3 ，…P 0n 、P 0pn ; S02. Fitted curve; Based on the existing total precordial pressure and total ejection pressure sequences corresponding to S01, a quadratic curve is fitted to obtain a quadratic polynomial. P 0 =a×P 0p 2 +b×P 0p +c ;in, P 0 For total anterior chamber pressure and P 0p The total ejection pressure; to ensure data accuracy, the coefficients of the quadratic polynomial are required. a, b, c The number of decimal places shall not be less than 6; S03. Calculate the static pressure of the wind tunnel to be simulated based on the simulated height; Based on simulated height H Calculate the static pressure in the wind tunnel that needs to be simulated. p The specific formula is as follows: ; S04. Calculate the total pressure in the anterior chamber; The wind tunnel static pressure obtained from S03 p The total pressure in the anterior chamber was calculated based on the experimental Mach number M. P 0 ; ; S05. Calculate the total ejector pressure; The total anterior chamber pressure obtained from S04 P 0 Substituting the quadratic polynomial corresponding to S02, we obtain the total ejection pressure required for the simulated height at the experimental Mach number M. P 0p .

[0007] The method for determining the total ejector pressure in a high-speed free-jet wind tunnel according to the present invention analyzes data from previous experiments to find and fit the total pressure in the forecourt under conditions of the same experimental Mach number M and similar model blockage. P 0 and total ejection pressure P 0p The quadratic curve establishes the total anterior chamber pressure. P 0 and total ejection pressure P 0p The existence of a quadratic function relationship allows us to obtain the total ejector pressure corresponding to the static pressure of any test chamber under the same experimental Mach number M and similar model blockage degree. This saves a lot of commissioning trips and energy consumption, improves the experimental efficiency of high-speed free jet wind tunnels, and has practical engineering value. Attached Figure Description

[0008] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0009] Figure 1 This is a flowchart of the method for determining the total ejector pressure of a high-speed free jet wind tunnel according to the present invention; Figure 2 Total anterior chamber pressure obtained for the example P 0 and total ejection pressure P 0p The quadratic curve obtained by fitting. Detailed Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0011] Example: Figure 1 As shown, the method for determining the total ejector pressure of a high-speed free-jet wind tunnel in this embodiment includes the following steps: S01. Select experimental data; By selecting three or more existing test data with the same experimental Mach number M, similar model blockage degree, and different ejector total pressure, the corresponding anterior chamber total pressure and ejector total pressure sequences were obtained: P 01 、P 0p1 ，P 02 、P 0p2 ，P 03 、P 0p3 ，…P 0n 、P 0pn ; S02. Fitted curve; Based on the existing total precordial pressure and total ejection pressure sequences corresponding to S01, a quadratic curve is fitted to obtain a quadratic polynomial. P 0 =a×P 0p 2 +b×P 0p +c ;in, P 0 For total anterior chamber pressure and P 0pThe total ejection pressure; to ensure data accuracy, the coefficients of the quadratic polynomial are required. a, b, c The number of decimal places shall not be less than 6; S03. Calculate the static pressure of the wind tunnel to be simulated based on the simulated height; Based on simulated height H Calculate the static pressure in the wind tunnel that needs to be simulated. p The specific formula is as follows: ; S04. Calculate the total pressure in the anterior chamber; The wind tunnel static pressure obtained from S03 p The total pressure in the anterior chamber was calculated based on the experimental Mach number M. P 0 ; ; S05. Calculate the total ejector pressure; The total anterior chamber pressure obtained from S04 P 0 Substituting the quadratic polynomial corresponding to S02, we obtain the total ejection pressure required for the simulated height at the experimental Mach number M. P 0p .

[0012] This embodiment obtains as follows: Figure 2 The total pressure of the anterior chamber shown P 0 and total ejection pressure P 0p The quadratic fitting curve. The method for determining the total ejector pressure in a high-speed free-jet wind tunnel according to the present invention has been successfully applied in high-speed free-jet wind tunnels.

[0013] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for determining the total ejector pressure of a high-speed free-jet wind tunnel, characterized in that, The determination method includes the following steps: S01. Select experimental data; By selecting three or more existing experimental data points with the same experimental Mach number M, similar model blockage degree, and different ejector total pressures, the anterior chamber total pressure sequence was obtained: P 01 , P 02 , P 03 , … , P 0n And the corresponding total ejection pressure sequence: P 0p1 , P 0p2 , P 0p3 , … , P 0pn ; S02. Fitted curve; Based on the existing total precordial pressure and total ejection pressure sequences corresponding to S01, a quadratic curve is fitted to obtain a quadratic polynomial. P 0 =a×P 0p 2 +b×P 0p +c ;in, P 0 Total pressure of the anterior chamber P 0p Total ejection pressure; coefficients of the quadratic polynomial a, b, c The number of decimal places shall not be less than 6; S03. Calculate the static pressure of the wind tunnel to be simulated based on the simulated height; Based on simulated height H Calculate the static pressure in the wind tunnel that needs to be simulated. p The specific formula is as follows: ； S04. Calculate the total pressure in the anterior chamber; The wind tunnel static pressure obtained from S03 p The total pressure in the anterior chamber was calculated based on the experimental Mach number M. P 0 ; ； S05. Calculate the total ejector pressure; The total anterior chamber pressure obtained from S04 P 0 Substituting the quadratic polynomial corresponding to S02, we obtain the total ejection pressure required for the simulated height at the experimental Mach number M. P 0p .

Images